1. Field of the Invention
This invention relates to time correcting circuits for timepieces with electrochromic displays, and more particularly to a time correcting circuit which enables fast correction of the time in an electrochromic display.
2. Prior Art
Recently electrochromic (hereinafter referred to as EC) display elements have been put to practical use in digital or analog displays for electronic timepieces and such timepieces that utilize a EC display element provide better display action than conventional light emitting diodes or liquid crystal displays. The EC display element utilizes an electrochromic phenomenon wherein the application of a voltage to the EC material provided between two electrodes colors or discolors the material by an oxidation-reduction reaction. Biologen compounds, WO.sub.3 in a thin film, etc. are known EC materials. Being different from light emitting diodes, EC elements can function with small electric current consumption and can provide a clear display under direct sunlight. In comparison with liquid crystal display, the EC display can obtain extremely vivid coloring and clear displays from all directions. In other words, the EC display does not have visual angle dependency and is preferable for the time display element for an electronic timepiece. The EC display is further characterized in that it provides a non-volatile memory function in that the color remains for a certain amount of time without the application of a voltage after coloring.
However, the EC display must be changed by a reverse voltage in order to erase the display due to the non-volatile characteristic thereof. This has a drawback in that the speed of writing and erasing is comparatively slow. It ordinarly takes about 1 to 2 seconds for writing and erasing and such time normally does not produce any problems during ordinary operation of the time display. However, in the case of time correction such slow speed of writing and erasing restricts the time required for correction of the time and fast correction of the EC display cannot be obtained.